In the prior art, there is described an air conditioning device like that indicated in Japanese Laid-open Patent Application No. 61-262560, having a compressor, an indoor heat exchanger, a throttle device (main valve), and an outdoor heat exchanger. This air conditioning device is capable of a heating mode in which a refrigerant is circulated through the compressor, the indoor heat exchanger, the main valve, and the outdoor heat exchanger in the stated order, and also has a discharge-intake bypass circuit allowing the refrigerant to bypass from the discharge side of the compressor to the intake side of the compressor during heating mode. The design of this air conditioning device is such that, during positive cycle defrosting mode to defrost the outdoor heat exchanger while circulating the refrigerant through the compressor, the indoor heat exchanger, the main valve, and the outdoor heat exchanger in the stated order, a valve (superheat valve) on the discharge-intake bypass circuit is opened, allowing the refrigerant to bypass from the discharge side of the compressor to the intake side of the compressor through the discharge-intake bypass circuit.